Reduced mobility is one of the most debilitating consequences of vision loss for more than three million Americans with low vision. We define visual accessibility as the use of vision to travel efficiently and safely through an environment, o perceive the spatial layout of key features in the environment, and to keep track of one's location in the environment. Our goal is to create tools to enable the design of safe environments for the mobility of low-vision individuals, including those with physical disabilities and to enhance safety for older people and others who may need to operate under low lighting and other visually challenging conditions. We plan to develop a computer-based design tool enabling architectural design professionals to assess the visual accessibility of a wide range of environments (such as a hotel lobby, subway station, or eye-clinic reception area). This tool will simulate such environments with sufficient accuracy to predict the visibility of key landmarks or hazards, such as steps or benches, for different levels and types of low vision, and for spaces varying in lighting, surface properties and geometric arrangement. Our project addresses one of the National Eye Institute's program objectives: Develop a knowledge base of design requirements for architectural structures, open spaces, and parks and the devices necessary for optimizing the execution of navigation and other everyday tasks by people with visual impairments. Our research plan has three specific goals: 1) Empirical: determine factors that influence low-vision accessibility related to hazard detection and navigation in real-world spaces. 2) Computational: develop working models to predict low vision visibility and navigability in real-world spaces. 3) Deployment: translate findings from basic vision science and clinical low vision into much needed industrial usage by producing a set of open source software modules to enhance architectural and lighting design for visual accessibility. The key scientific personnel in our partnership come from three institutions: University of Minnesota -- Gordon Legge and Daniel Kersten; University of Utah -- William Thompson and Sarah Creem-Regehr; and Indiana University -- Robert Shakespeare. This interdisciplinary team has expertise in the necessary areas required for programmatic research on visual accessibility -- empirical studies of normal and low vision (Legge, Kersten, Creem-Regehr, and Thompson), computational modeling of perception (Legge, Kersten, and Thompson), computer graphics and photometrically accurate rendering (Thompson & Shakespeare) and architectural lighting design (Shakespeare). We have collaborative arrangements with additional architectural design professionals who will participate in the translation of our research and development into practice.